This invention relates to hand tools, and in particular the invention is concerned with a hand tool for projecting a reference beam of visible light for precise alignment on floors and walls.
For some time laser beams have been used in construction for level references, vertical references and layout on floors and walls. Typically a construction worker marks the floor or walls indicating the location of walls, windows, or other building elements to be constructed. A chalk line is often used to permanently mark the walls or floors. This is a two man job with one man holding one end of the chalked string while the other snaps it, releasing chalk dust which makes the mark.
The most common prior laser device is a simple carpenter""s level with level vials and with a laser beam projector attached. See FIG. 1. Many thousands of these are in use today. U.S. patents in this area include Genho U.S. Pat. No. 4,221,483, Rando U.S. Pat. No. 6,009,630 and others. Although indicating level, these levels do a poor job of projecting a beam on a floor or wall. LeveLite Technology, Inc., the assignee of this invention, makes a product for producing two beams of visible light on the floor for the purpose of laying out a 90xc2x0 corner. It is described in U.S. patent application No. Ser. No. 09/264,371, U.S. Pat. No. 6,202,312, incorporated herein by reference. This instrument uses a collimated beam of light and an adjustable cylinder lens to convert the round beam into a fan of light and thus project a line on the surface. This is not a very efficient use of the laser diode light because of the natural divergence of the diode and cropping of the beam in collimation. Typically the laser diode beam divergence is 30xc2x0 in one axis and 8xc2x0 on the transverse axis. About half the light is lost in the collimation process. In addition, the line can be focused for only one distance. Such an optical system is shown in plan view in FIG. 2 herein and in side view in FIG. 3 herein, and is the present state of the art. Both the problems of efficient use of the laser light and focusing continuously along a line are solved by the current invention.
This invention allows the user to project a highly visible line on a surface. In addition it allows the line to be adjusted to true vertical or horizontal with the aid of a level vial when used on a vertical surface, e.g. a wall. An attachment to a stud-finder instrument is further provided. In some cases a magnet facilitates holding the unit to metal studs. The instrument is partially described in Disclosure Document No. 476310.
The simple, efficient optical system is the important feature of this invention. The instrument provides a highly visible line which can temporarily act as a chalk line for the purpose of marking points along the line, when requiring a more permanent mark, or for operations along the line with the laser line in place. These and other objects, advantages and features of the invention will be apparent from the following description of a preferred embodiment, considered along with the accompanying drawings.